Oil soluble amine salts of long chain alpha-sulfocarboxylic acids



atent 3,048,007 Patented Aug. '7, 1 962 fifice 3,048,607 01L SOLUBLE AMINE SALTS F LONG CHAIN ALPHA-SULFOQARBOXYLIC ACIDS Elizabeth L. Fareri and John P. Pellegrini, J12, Pittsburgh, Pa, assignors to Gulf Research 8: Development Company, Pittsburgh, Pa., a corporation of Delaware N0 Drawing. Filed Dec. 22, 1958, Ser. No. 781,907

8 Claims. (Cl. 260-401) This invention relates to novel addition agents for hydrocarbon lubricating oils having the nature of detergents. In particular the invention relates to new oilsoluble salt compositions. The invention is also concerned with compounded hydrocarbon lubricating oils containing such salt compositions.

In the lubrication of internal combustion engines of all types, particularly when severe operating conditions are encountered, uncompounded lubricating oils are frequently found to be objectionable because they fail to prevent deposition of. sludge, carbonaceous materials or varnish on the engine parts, and rust or corrosion of metal parts contacted thereby. To overcome these and other deficiencies one or more addition agents are frequently employed in conjunction with hydrocarbon lubricating oils. For example, in order to counteract the tendency of lubricating oils to form deposits of gum and sludge, additives of a detergent nature may be incorporated in such oils.

We have found that lubricating oils having improved detergency characteristics can be obtained by incorporating therein a small amount of a sulfonate salt of (I) an oil-soluble primary, secondary, or tertiary monoor diamine that contains a total of at least 7 carbon atoms per molecule and that contains at least one N-substituent selected from the group consisting of (a) open-chain aliphatic hydrocarbon radicals containing 3 to 22 carbon atoms, (b) aralkyl radicals containing 7 to 24 carbon atoms, and (II) a partial ester of an aliphatic monohydric alcohol that contains 8 to 22 carbon atoms per molecule and an alpha-sulfo fatty acid that contains 12 to 22 carbon atoms per molecule. Sulfonate salts of oilsoluble amines and partial esters of alpha-sulfostearic and alpha-sulfopalmitic acid are especially elfective for the purposes of this invention, particularly the sulfonate salts of branched-chain alkyl amines and branched-chain alkyl esters of such alpha-sulfo fatty acids, preferred examples of such salts being the Oxo octylammonium sulfonate of Oxo octyl alpha-sulfostearate, the Z-ethylhexylaminopropylarnine sulfonate salt of Oxo octyl alpha-sulfostearate, and the di(0xo octyl) ammonium sulfonate salt of Oxo octyl alpha-sulfostearate. The present invention, based on the above-indicated finding, relates to compounded hydrocarbon lubricants containing sulfonate salts of the class indicated above, to the sulfonate salts as such, and to the preparation of such salts.

The sulfonate salts of this invention can be prepared in any suitable manner. In accordance with the present invention, the salts are prepared by first partially esterifying the desired alpha-sulfo fatty acid with an equivalent proportion of an aliphatic monohydric alcohol of the class disclosed herein, followed by neutralization of the resultant partial ester with an approximately equivalent proportion of a monoamine of the class disclosed herein, or with a diamine of the class disclosed in the proportion of l to 2 equivalents of amine, preferably 1, per equivalent of partial ester. The term neutralized and the like as used herein is used merely to indicate the reaction of an acidic group with a basic group, as the resultant salt need not have a pH of 7.

Conventional esterification conditions are employed during the esterification reaction. Thus, the reaction can be carried out either with an equivalent proportion of alcohol or with an excess of alcohol. Although the reaction can proceed slowly to equilibrium at ambient atmospheric conditions, completion of the reaction is facilitated by effecting the reaction at a temperature sufficient to remove Water of esterification from the reaction. For example, esterification can be carried out at a temperature of F. to 350 F., preferably 210 F. to 300 F. In no case should a temperature suflicient to cause decomposition of the reactants or the reaction product be employed. Also, the reaction temperature is preferably below the boiling point of the lower boiling reactant, so as to avoid unnecessary loss of this reactant from the reaction mixture. Usually a reaction time of about 0.5 to 6 hours will be suflicient to carry the esterification reaction to equilibrium or completion when heating is employed. If desired the reaction can be carried out in the presence of .a solvent that will form a low boiling azeotrope with water formed during esterification, so as to facilitate removal of the water from the reaction. Examples of such solvents are benzene and toluene. Also the reaction can be carried out in the presence of an esterification catalyst if desired, such as sulfuric acid or p-toluenesulfonic acid, but this is not essential.

During the esterification reaction, the alcohol reacts preferentially with the carboxyl group of the alpha-sulfo fatty acid to form a carboxylate ester containing an unneutralized sulfo group. This is true even when the alcohol is employed in a substantial excess as the sulfo group is not readily esterified under the conventional conditions described herein.

In order to form the sulfonate salt reaction products of this invention, the alpha-sulfo fatty carboxylate ester, obtained as described above, preferably after separation of unreacted alcohol, if any, by distillation or other conventional procedure, is then neutralized with the desired amine. The neutralization reaction ordinarily takes place spontaneously at room temperature, normally with evolution of heat. In some cases it even may be desirable to control the rate of addition of the amine to the reaction mixture in order to maintain the reaction temperature below 180 F., preferably below 140 F. On the other hand, in the case of less reactive amines and alpha-sulfo fatty acid esters, it may be desirable to heat the reaction mixture, say to 140 F. or 180 F., in order to accelerate the neutralization reaction. We prefer to react the amine and ester in proportions that will result in the substantially neutral product, as such products normally exhibit superior detergent properties, except in instances where the unreacted diamine also possesses good detergent properties. By substantially neutral product, or the like, is meant a product resulting from neutralization of an alpha-sulfo fatty acid ester with approximately an equivalent proportion of the desired amine.

Alpha-sulfo fatty acids that can be used in the synthesis of the sulfonate salts of this invention are those containing 12 to 22 carbon atoms per molecule. The acids may be saturated or unsaturated. The alpha-sulfo fatty acids that contain 14 to 18 carbon atoms form especially effective detergent salts and therefore are especially preferred. Examples of such acids are alpha-sulfostearic and alphasulfopalmitic acids. Examples of other acids that can be used are alpha-sulfolauric, alpha-sulfomyristic, alphasulfooleic and alpha-sulfob-ehenic acids. It is important that the sulfo group be attached to the alpha-carbon atom, as the derivatives of such acids exhibit unusual stability and resistance to hydrolysis under both acidic and alkaline conditions. These features are important for lubricant additives since such materials are customarily required to function under acidic or basic conditions at elevated temperatures in the presence of water, and since the unhydrolyzed materials disclosed herein are substantially more efficient detergents in lubricating oils than the products of hydrolysis.

'Any aliphatic monohydric alcohol containing 8 to 22 carbon atoms per molecule can be used in the esterification of the alpha-sulfo fatty acids disclosed herein. Especially efiective addition agents, insofar as detergency in lubricants is concerned, are obtained with unsubstituted saturated aliphatic monohydric alcohols containing 8 to 13 carbon atoms, especially primary alcohols having substantial chain branching, examples of which are 2-ethylhexyl alcohol, Oxo octyl alcohol, OX tr-idecyl alcohol, and the like. Other alcohols the use of which is included by the present invention are lauryl alcohol, stearyl alcohol, myristyl alcohol, oleyl alcohol, and n-docosyl alcohol. It is not necessary that the alcohols employed be pure compounds, as mixtures of alcohols derived from naturally occurring substances, for example, mixed C predominantly C alcohols derived from coconut oil fatty acids, and the like, can be used. The use of the higher molecular weight alcohols disclosed herein is important to insure oil-solubility, in detergent proportions, of the ultimate derivatives.

Amines than can be used to form the sulfonate salts of this invention can be any of the class of primary, secondary, and tertiary monoor di-amines that contain a total of at least 7 carbon atoms per molecule, and that contain at least one N-substituent of the group consisting of (a) open-chain aliphatic hydrocarbon radicals containing 3 to 22 carbon atoms, and (b) aralkyl radicals containing 7 to 24 carbon atoms. The other N-substituents of the amines can be hydrogen or low molecular weight substituents, i.e., C radicals, such as methyl or ethyl, alkylol groups such as ethylol and propylol, aromatic groups such as phenyl or tolyl or benzyl, provided that such other substituents do not adversely affect the oilsolubility, stability, antirust, or detergent characteristics of the salts derived from such amines. Alternatively, such other substituents can be of the same class as the first-mentioned N-substituent. Especially good results have been obtained with branched-chain alkyl primary and secondary monoand di-amines, particularly those containing a branched-chain aliphatic hydrocarbon substituent, examples of which are Ox-o octylamine, di(Oxo octyl) amine and Z-ethylhexylaminopropylamine. However, the invention is not limited to such amines and other amines of the disclosed class can be used. For example, there can be used primary alkyl amines such as t-octylamine, and n-dodecyl-amine, aralkyl amines such as benzyl-amine, diamines such as N-octadecenyl ethylenediamine, 3 octadecenylaminopropylamine, N,N di secbutyl-p-phenylenediamine, and heterocyclic amines such as 1-isopropyl-2-methyl-2-heptylhexahydropyrimidine and the like. As in the case of the alcohols, it is not necessary that the amines employed in the preparation of the sulfonate salts of this invention be pure compounds, and mixtures can be used. For example there can be used primary, secondary and tertiary amines Whose substituents are derived from fatty acids obtained from naturally occurring fats and oils such as coconut oil, tallow and the like. In such cases the N-substituents of the amines will be straight-chain aliphatic hydrocarbon radicals that contain even numbers of carbon atoms from 8 to 22. Examples of such amines include cocoamine, dicocoamine, cocodimethyl'amine, 3 tallow-alkylaminopropylamine, N-tallow alkyl ethylenediamine, 3-s0ya alkylaminopropylamine, and the like. Neutralization of the alphasulfo fatty acid esters with the relatively high molecular weight amines disclosed herein insures oil-solubility in lubricating oils in a proportion sufficient to provide good detergency. Detergents prepared from the amines are also ashless.

The preparation of sulfonic acid salts of this invention is further illustrated by the following specific examples which constitute preferred embodiments of the invention:

EXAMPLE I 0x0 octyl alcohol, consisting of mixed, highly branchedchain isomeric alcohols, principally dimcthylhexanols, in the amount of 0.1 mol (13.1 grams), is added to 0.1 mol (36.5 grams) of alpha-sulfostean'c acid in ml. of previously dried benzene. The reaction mixture is heated under reflux for approximately 1.25 hours, water of esterification being removed in the form of a low boiling azeotrope with benzene. The solution is then cooled to approximately 100 F. Oxo octylamine (mixed primary amines derived from Oxo octyl alcohol) is gradually added to the reaction mixture with stirring in an approximately equivalent proportion of 0.108 mol (13.9 grams), in order to neutralize the Oxo octyl alpha-sulfostearate obtained during the esterification reaction. The neutralization reaction is exothermic. The neutralization product is cooled to room temperature and filtered to remove solids. The solvent is then removed by distillation at reduced pressure. The resulting product, consisting essentially of the sul'fonate salt of 0x0 octylamine and 0x0 octyl alpha-sulfostearate, hereinafter referred to as compound A, is recovered as a liquid in the amount of 60.7 grams. A product prepared as described had the following analysis:

To a benzene solution of 0.1 mol of 0x0 octyl alphasulfostearate prepared as described in Example I, there is added at an initial temperature of about 75 F. sufiicient di(Oxo octyl)arnine (29.0 grams; 0.12 mol) to neutralize the reaction mixture. The reaction proceeds spontaneously with evolution of heat. After completion of the reaction, the reaction mixture is cooled to room temperature and filtered. Benzene and any unreacted amine still present are removed by distillation at subatmospheric pressure. The resultant liquid product, consisting essentially of the sulfonate salt of di(Oxo octyl) amine and OX0 octyl alpha-sulfostearate, hereinafter referred to as compound B, is recovered in the amount of 75.9 grams. A product prepared as described had the following analysis:

Actual Theoretical for (CsH17)zNH-CmHsaCHSOaHCOOCtHH N, percent- 1. 89 1. S, percent... 4. 16 4. 46

EXAMPLE III a a pound C, is recovered in the amount of 57.8 grams. A The foregoing examples are illustrative only, and product prepared as described had the following analysis: other products of the class disclosed herein can be Actual Theoretical for CsHnNHCI-IzCHzGHzNHz(CmHssCHSOsIlCOO(3811102 N, percent- 2.99 l 2. 46 S, percent... 5. 34 5. 63

EXAMPLE IV similarly prepared using the same or equivalent amines,

alcohols and/ or alpha-sulfo fatty acids, with good results. Example I is dissolved in benzene in the amount of 0.079 For exam? 16 there can be 'supstimted in foregoing mol and the resulting solution is filtered. To this soluexamp m i same or equlYaient .pwpomons tionthere is then added 19 0 grams (0 079 m 01) of sulfolauric acid, alpha-sulfomyristic acid, alpha-sulfoolelc propyhlm eth e ptyLhex ahy dro pyrimi dine) AS in ac1d,and alpha-sulfobehenic acid. For the amines there the preceding examples, the neutralization reaction is can be slibsmuted m i same or eqiuvalent proPomons exothermic. Solvent and unreacted amine are removed lauiylamme Cocoamme 't'oiztylamme ?ocodlmethyl from the reaction mixture by distillation at reduced presand tzfuow 'alkylalemopmPylamme- For the sure. The viscous liquid product, consisting essentially alcohols f m'the foregomg exarflples there be of the sulfonate Salt of 1 1 employed instead, in the same or equivalent proportions, hexahydropyrimidine and 0x0 octyl alpha-sulfostearate, z-ethylhexyl alcohol, ll 211601101, l 0163/1 31601101- Oxo octyl alpha-sulfostearate prepared as described in hereinafter referred to as compound D, is recovered in the The Sulfonflte a s f t s inv ntion are effective in amount of 54.9 grams. A product prepared as described improving the detergent and antirust properties of hydrohad the following analysis: carbon lubricating oil compositions; For such purposes Theoretical for Actual C3H7NOCH3C1H15NH(OH2)ZOH2-CMHBSOHSOBHCOOOQHH N, percent.-- 3. 23 3. 91 S, percent--- 4. 50 4.47

EXAMPLE V small amounts of sulfonic acid salts are generally sufficient. For example, the sulfonalt'e salts of the present invention can be added to hydrocarbon lubricating oils in minor amounts, say from 0.01 to 0.1 percent by Weight of thehydrocarbon oil, in which proportions rust formation of metal surfaces contacted by the oil will be inhibited. Larger amounts of the sulfonic acid salts disclosed herein, say from about 0.1 to about 20 percent by weight of the hydrocarbon oil, confer excellent detergent properties on the oil solution. For detergent lubricants employed in the lubrication'of internal combustion engines we particularly prefer to employ the The 1:1 mol ratio salt of 0x0 octyl alpha-sulfostearate and N,N'-di-sec-butyl-p-phenylenediamine (compound E) is prepared similarly as in Examples II, III, and IV by reacting 0.109 mol (51.8 g.) of Oxo octyl alpha-sulfostea- 45 rate with 0.1 mol (24.02 g.) of the diamine. Product yield is 75.9 g. Analysis of the product is as follows:

Ac- Theoretical for 50 tual CiH NHC HlNHC4H -C H CHSOsHCOOCs n gf' l'ii iii'jj i132 i123 sulfonic acid salts of this invention in proportions in the range of about 1 to 10 percent by Weight of the hydro- EXAMPLE VI carbon oil.

The utility of the herein disclosed sulfonic acid salts The 2:1 mol ratio salt of 0x0 octyl alpha-sulfostearate as detergents in lubricating oil compositions has been and N,N'-di-sec-butyl-p-phenylenediamine (compound F) demonstrated by subjecting various mineral lubricating is prepared similarly as in Example V by reacting 0.1 mol oil samples containing representative salts within the (47.6 g.) of the alpha-sulfo fatty acid ester with 0.054 mol scope of this invention to various test procedures. Thus, (12.02 g.) of the diarnine. Product yield is 60.0 g. separate samples of paraifinic lubricating oils contain- Analysis of the product is as follows: "ing compounds A, B, C, and D in the amount of 5 per- Theoretical for Actual C4H7NHC5H4NHC4H7-(CmHxsCHSOsHGOOCBHflh N, percent.-- 2. 56 2. 39 S, percent..- 4. 81 5.

EXAMPLE VII cent by weight of the baseoil, and compounds E,"F,

and G in the amount of 3 percent by weight of the base 5 oil, were subjected to a test adapted to evaluate the detergency or deposibpreventing characteristics. Briefly, in accordance with this test, the oil sample to be tested, preheated to a tempenature of about 150 to 165 F. in a reservoir provided with a heating means'and an oil The benzylamine salt of Oxo octyl alpha-sulfostearate (compound G) is prepared similarly as in Example VI by reacting 0.0754 mol (36 g.) of the ester with 0.0754 mol (8.1 g.) of the amine. Product yield is 45.9 g. Analysis of the product is as follows:

' splashing means comprising a number of stainless steel Actual g a g fifi g wires-attached to a rotatable steel shaft, is splashed on the surface of a prepolished and taredl aluminum test Npmentflui 243 240 panel heated to a temperature of 500 F. Air is intro- S,percent.-- 5.39 5.48 duced into the oil reservoir at the rate of ten liters per hour for the eight-hour test period. At the conclu'sion of the test, the panel is removed and allowed to drain and cool. After cooling, the test panel is washed free from oil, dried and reweighed. The increase in weight of the panel in milligrams is recorded. The oil employed in the tests involving compounds A, B, C, and D was a parafiinic lubricating oil prepared by solvent treatment of a lubricating oil distillate derived from a Mid-Continent crude oil. A sample of the test oil had the following properties:

Neutralization value, ASTM D974 total acid The results of thdforegoing tests are presented in the table below:

Table A Deposit Weight, mg.

Example No. Test composition Base oil Base oil plus 5% compound A Base oil plus 5% compound B Base 011 plus 5% compound Base oil plus compound D Base oil Base oil plus 3% compound motto ase o Base oil plus 3% compound F Base on Base oil plus 3% compound G O) s e 's s s e From the results presented in Table A it will be seen that the sulfonate salts prepared in accordance with this invention eflected a marked reduction in the insoluble deposits formed on the aluminum test panel.

The detergency characteristics of a representative sulfonate salt of this invention were further demonstrated by subjecting a mineral lubricating oil containing 5 percent of compound A to a test in a Lauson single cylinder engine. Briefly, according to this test, the test oil is placed in a crankcase of a single cylinder Lauson diesel engine. The engine is operated under a 3 hp. load at 1860 r.p.m., while maintaining a cooling jacket temperature of 300 F., a crankcase temperature of 225 F. and an auto-fuel ratio of 13:1. At the end of 24 hours operation under these conditions, the engine is stopped, disassembled and the engine is examined for stuck rings (three possible), oil channel plugging (100 percent possible), piston varnish, and bearing weight loss. The engine is given an overall merit rating based on a scale of percent for no stuck rings, 45 percent for no piston varnish, and 45 percent for no oil channel blocking. The piston varnish rating is obtained by comparing a piston with a set of prepared standards and given a rating from 0 to 10 in ascending order of merit. The base oil employed in this test was a parafiinic lubricating oil derived by solvent-treating a lubricating distillate derived from a Mid-Continent type crude oil. A sample of the base oil had the following properties: Inspections:

Gravity, API 28.3 Viscosity, SUV, sec.:

100 F 464 210 F- 62.1 Viscosity index 99 Color, ASTM union 2 Carbon residue, Conradson, percent 0.05 Neutralization value, ASTM D974 total acid The results of the foregoing tests are presented in the table below:

From the results in the preceding table, it Will be seen that good detergency is obtained in an engine lubricated with an oil containing a salt of the class disclosed herein.

It will be understood that the invention is not limited to the specific lubricating oil compositions disclosed above and that other sulfonate salts of the class disclosed herein can be employed with good results. For example, there can be substituted in the foregoing specific embodiments, in the same or equivalent proportions, the sulfonate salts of cocoamine and 3-talloW-alkylaminopropylamine and 2-ethylhexyl, lauryl, tridecyl, myristyl, and oleyl alpha-sulfostearates, alpha-sulfolaurates, alphasulfopalmitates, alpha-sulfooleates, alpha-sulfomyristates, and alpha-sulfobehenates.

The term Oxo as applied to various alkyl groups herein is used in its normal sense to mean the mixed isomeric alkyl radicals derived from Oxo alcohols. By Oxo alcohols is meant mixed isomeric alcohols prepared by the Oxo synthesis process. As is Well known the Oxo synthesis process involves the catalytic hydroformylation of mixed monoolefins, such as are obtained by the catalytic polymerization of low molecular weight monoolefins obtained from petroleum refinery gases, to produce a mixed isomeric aldehyde product, followed by catalytic hydrogenation to produce mixed isomeric primary alcohols having one carbon atom per molecule more than the number of carbon atoms in the olefins subjected to hydroformylation.

To the lubricant compositions of the present invention there can be added one or more other addition agents adapted to improve the compositions in one or more respects. For example, there can be added to the lubricant compositions of this invention, pour point depressants, extreme pressure agents, viscosity index improvers, anti-wear agents, corrosion inhibitors, other detergents and the like. Although the invention has been described particularly with reference to lubricating oil compositions, it will be understood that other lubricant compositions such as greases, are included by the invention.

The use of the sulfonate salts of this invention is not confined to lubricants, as such salts also Will produce an improvement in the combustion characteristics of fuel oils, and will reduce engine-stalling due to carburetor icing when employed in gasolines.

Numerous modifications and variations of the invention as here set forth can be resorted to Without departing from the spirit and scope of the invention. Accordingly, only such limitations should be imposed as are indicated in the claims appended hereto.

We claim:

1. A sulfonate salt of (-I) an oil-soluble amine selected from the group consisting of primary, secondary, and tertiary monoand di-amines that contain a total of at least 7 carbon atoms and that contain at least one N- snbstituent selected from the group consisting of (a) open-chain aliphatic hydrocarbon radicals containing 3 to 22 carbon atoms, and (b) aralkyl radicals containing 7 to 24 carbon atoms, and (II) a partial ester of an aliphatic monohydric alcohol that contains 8 to 22 carbon atoms per molecule and an alpha-snlfo fatty acid that contains 12 to 22 carbon atoms per molecule.

2. A substantially neutral sulfonate salt of octylamine and octyl alpha-sulfostearate.

3. A substantially neutral sulfonate salt 'of dioctylamine and octyl alpha-sulfostearate.

4. A substantially neutral sulfonate salt of 2-ethylhexylaminopropylamine and octyl alpha-sulfostearate.

5. A 1:1 mol ratio salt of 1-isopropyl-2-rnethy1-2heptylhexahydropyrimidine and octyl alpha-sulfostearate.

6. A 1:1 mol ratio salt of octyl alpha-sulfostearate and N,N'-di-sec-butyl-p-pheny1enediamine.

7. A substantially neutral salt of octyl alpha-sulfostearate and N,N-di-sec-butyl-p-phenylenediamine.

8. A substantially neutral salt of benzylamine and octyl alpha-sulfostearate.

References Cited in the file of this patent UNITED STATES PATENTS Epstein et al Oct. 31, 1939 Wilson Apr. 21, 1942 Datin et al. July 13, 1943 Robinson et a1 Sept. 7, 1943 Ruedrich Jan. 16, 1945 Kelley et al. Apr. 3, 1945 FOREIGN PATENTS Canada Jan. 31, 1956 

1. ASULFONATE SALT OF (1) AN OIL-SOLUBLE AMINE SELECTD FROM THE GROUP CONSISTING OF PRIMARY, SECONDARY, AND TERTIARY MON- AND DI-AMINES THAT CONTAIN A TOTAL OF AT LEAST 7 CARBON ATOMS AND THAT CONTAIN AT LEAST ONE NSUBSTITUENT SELECTED FROM THE GROUP CONSISTING OF (A) OPEN-CHAIN ALIPHATIC HYDROCABON RADICALS CONTAINING 3 TO 22 CARBON ATOMS, AND(B) ARALKYL RADICALS CONTAINING 7 TO 24 CARBON ATOMS, AND (11) A PARTICAL ESTER OF AN ALIPHATIC MONOHYDRIC ALCOHOL THAT CONTAINS 8 TO 22 CARBON ATOMS PER MOLECULE AND AN ALPHA-SULFO FATTY ACID THAT CONTAINS 12 TO 22 CARBON ATOMS PER MOLECULE. 